Field of the Invention
The present invention relates to a solar collector, a method for producing a light-absorbing surface, and a use of a surface for light absorption or emission of heat.
Description of the Background Art
Thermal solar installations, such as for hot water production, nowadays are equipped with absorbers whose surfaces are colored black with paints or galvanic coating. Today, such coatings serving as absorbers must be applied post-production to a solar collector with a variety of methods such as painting or galvanic coating. A coolant for removal of the heat is made to flow around these absorbers.
Consequently additional, post-production, polluting application methods (such as chromating) using chemicals or polymers are necessary on heat transmission surfaces. Coatings with polymers are unstable over time in sunlight, so that efficiency losses occur. In addition, the heat energy must overcome the interfaces between the coating and metallic heat exchanger surfaces.
DE 103 61 910 B3 is concerned with a method for paint-free blackening of the surfaces of components including aluminum materials with high silicon content, in which the surface is first prepared using various methods. After a rinsing process, the blackening is obtained by a treatment in an aqueous active solution containing zinc sulfate, ethylenediamine, and ammonium molybdate.
DE 10 2004 031 034 A1, which corresponds to U.S. Pat. No. 8,002,905, and which is incorporated herein by reference, describes a flux for soldering or brazing components. Here, one or more specific surface properties are to be produced as early as the soldering process. Corrosion-resistant, hydrophilic, or adhesive surfaces, as well as a decorative appearance, are made possible in this way.